Field of the Invention
The present invention relates to a heat exchanger.
Description of the Background Art
DE 10 2005 031 475 A1 discloses a heat exchanger which has a tube-fin block closed on both sides by a collecting box. For receiving a coolant each collecting box has two side walls, two end walls, a cover, and a bottom arranged opposite to the cover. The bottom thereby comprises one or more openings for receiving tubes of the tube-fin block. The cover has a recess into which a partition wall extends dividing the interior space of the collecting tank into two subchambers.
In the conventional are, if one of two subchambers is formed as a high-temperature chamber and the other of the two chambers as a low-temperature chamber, high stresses occur that extremely strain the heat exchanger in the area of the partition wall. If a coolant flows through the high-temperature chamber, thermal stresses are created in the tubes. The thus arising forces from the high-temperature chamber are the cause for a bottom-surface shifting relative to the low-temperature chamber to occur. The shifting causes an expansion of the tubes at the bottom connection. As a result, defects can arise in the area of the partition walls, which occur, for example, as cracks in the tubes.
To prevent such disadvantageous defects, DE 10 2007 044 742 A1 discloses a heat exchanger in which the two chambers are separated not only spatially but are configured having a distance from one another.
However, conventional heat exchangers comprise a more complex structure increasing the assembly effort and thereby the production costs of the heat exchanger. Moreover, this type of design does not guarantee the complete prevention of damage to the tubes. The heat exchangers do not allow a sufficient temperature expansion compensation, because the cover of the heat exchanger is made of a continuous sheet profile.